U.S. Swimmer Nyad Ending Cuba-Florida Crossing.

MIAMI (Reuters) - U.S. long-distance swimmer Diana Nyad decided on Sunday to abandon her third attempt to swim from Cuba to Florida after being stung overnight in the face and eyes by jellyfish, her team said.

Nyad, 62, had swum more than 77 miles of 103-mile stretch when she decided to end the effort later on Sunday. As of midday, the endurance athlete had made more than 114,000 swimming strokes since starting Friday evening, according to her website's tally.

"After more than 40 hours of swimming and two Portuguese Man-of-War stings, Diana Nyad decided to end her swim today ...," a posting on Twitter and her website said. "But, in unique and characteristic fashion, Nyad decided to complete this day."

Nyad was treated by doctors on a specially equipped boat accompanying her after she was stung on Saturday night.

"From the water, she called out to her flotilla of four escort boats and addressed each of them in a strong voice," a Nyad Twitter post said. "'The medical team said I should not go another two nights in the water and risk additional likely Man-of-War stings which could have a long term cumulative effect on my body.'"

The swim was the second time in two months Nyad had attempted the crossing. In August, she swam for 29 hours and about 50 miles before abandoning the effort. She said she suffered from asthma for 11 hours of the swim, which drained her strength.

Earlier on Sunday, Nyad had been swimming "stronger and stronger," a message said, after her pace slowed overnight when she was stung by Portuguese Man o'War and complained of breathing problems.

At one point in the swim, a white-tipped shark was spotted in her vicinity but eventually swam away as one of Nyad's safety divers approached it.

Even though she retired from competitive swimming years ago, Nyad has said she undertook the swim to help people her age and older realize they can still do many things. She said the swim also was an effort to improve U.S.-Cuba relations.

Nyad, who was raised in south Florida, first attempted the crossing from Cuba in 1978 when she was 28 and at her peak as a marathon swimmer. Heavy seas forced her to give up that try.

She has set several world records, including swimming around New York's Manhattan island in 1975 in less than eight hours and completing a 102.5-mile swim from Bimini in the Bahamas to Florida in 1979.

The Florida Straits crossing was completed in May 1997 by Australian Susan Maroney, then 22, but she swam in a cage to protect her from sharks. Nyad was being protected in the warm waters by an anti-shark device that uses a mild electrical current to shield her from the predators.